Waste disposal is a worldwide problem. One need only open a newspaper or turn on a television to witness problems encountered in efficiently disposing of waste. Concerns of pollution to land, water and air have resulted in statutes regulating the waste disposal industry. To comply with these statutes, many communities began disposing of waste in "sanitary" landfills. Unfortunately, landfills create many problems including ground water pollution and toxic leaks. Moreover, the large volume of waste generated is straining the capacity of landfills and many landfills are now full.
Some communities have turned to recycling waste. Unfortunately, low compliance with recycling ordinances together with pervasive amounts of non-recyclable waste have resulted in less than adequate results. Accordingly, there is an long felt need for an apparatus that permits recycling while reducing the volume of non-recyclable waste ultimately produced. The subject invention provides a solution to this problem.
Alternate forms of waste disposal are needed. Although, some communities dispose of waste by incineration, most incinerators produce noxious and toxic air emissions and/or insufficiently reduce waste volume. Current incineration systems typically reduce the waste to 15 to 30% (by weight), if the recyclable materials are removed from the feedstock prior to combustion. The large amounts of residual waste produced are the result of incomplete burning at excessively high temperatures in an attempt to economically handle huge volumes of waste on a continuous basis.
A particular problem of two-chamber modular incinerators, which have the advantage of efficient burning of certain very specific feedstock streams, is that in other applications, waste burnout is incomplete which increases ash residue quantities and reduces the efficiency of energy recovery. The subject invention overcomes this major deficiency of the typical two-chamber modular burn incinerator.
Incinerators using a primary combustion chamber operating using a substoichiometric amount of oxygen (air) and a secondary combustion chamber using a stoichiometric excess of oxygen (air) to insure complete combustion are known in the art (See, for example, U.S. Pat. Nos. 4,870,910 and 4,913,069, the contents of which are hereby incorporated by reference). However, no prior art reference teaches the advantages produced by cooling the flue gases generated from the first combustion prior to the second combustion (afterburn). By cooling these flue gases, the subject invention allows toxins and/or precursors of toxins, including fluorine, chlorine, volatile metals, and molecules involved in the formation of the super toxic organics, the dioxins and furans, to be condensed onto or as particulates (bottom ash) and removed prior to the second combustion. By removing particulate matter (bottom ash and fly ash) at this juncture, catalytic reactions on such ash, which comprise a primary mechanism for formation of the super toxic organics, are significantly precluded. This ultimately results in a cleaner gas being released to the atmosphere.
The method and apparatus of the subject invention solves a long existing problem and fulfills the long felt need for a high efficiency waste disposal system by providing a means for batch burning large quantities of waste that can be sorted for recyclable materials after burning. Non-recyclable residuals (ash) make up less than 3% of the original batch weight, and in the case of municipal waste, the ash can be processed to make cement. Removal of the recyclable materials is much easier after incineration due to the significantly smaller volume of residue. Moreover, differences in weight between metals, glass and ash facilitate sorting of the recyclable material. Medical or infectious waste residuals can also be disposed of using the subject invention.